In the proposed research, event-related brain potentials (ERPs) will be recorded from normal subjects and two populations of children (dyslexics; children at risk for schizophrenia) who display specific cognitive deficits. The endogenous brain potentials will be elicited during cognitive tasks designed specifically to tap the functions for which these disordered subjects show deficits. All subjects will be followed longitudinally so that both normal and abnormal developmental patterns of the brain's electrical activity, and the stability of brain-behavior relationships can be charted. Comparison of the disordered groups' endogenous ERPs with those recorded from the normal samples will allow an assessment of which stages of information processing are deficient in these populations. In the first phase of the research, a life span approach will be taken for the cognitive brain potential components with subjects from 6 to 80, so that a description and analysis for the changes in the normally-aging brain's electrical activity can be made. In the second phase, ERPs recorded from dyslexic subjects will be used to determine if neurophysiologically distinct subtypes of dyslexic children exist, with each characterized by different brain organizations. The main goal in the children at risk for schizophrenia portion of the proposal is to determine, using ERPs and autonomic responses, if there is a neurophysiologically deviant subgroup within the high risk sample, possibly the most vulnerable to the development of schizophrenia. The Principal Investigator will receive training in the neuropsychological assessment of brain-injured and learning disabled patients, in the application of topographical methods (both human and animal) to the cognitive ERPs, and in the application of genetic analyses to ERP data. This professional growth will aid in the development of new paradigms for the study of brain-behavior relationships, in localizing the areas of the brain that are dysfunctional in clinical groups, and in more precisely delineating ERP "markers" for such mental illnesses as schizophrenia and depression.